1. Field of the Invention
The present invention relates to the prevention of liquids into a gas chromatograph, and more particularly to an apparatus for allowing only gases to enter the gas chromatograph and not liquids.
2. Description of Related Art
A gas chromatograph is commonly used in the chemical industry for separating and analyzing a complex gaseous mixture. Oftentimes, the source of the gas mixture is a pipeline or a sample cylinder that contain liquids in addition to the gases to be separated. However, because the gas chromatograph is only capable of separating gases and not liquids, the intrusion of liquids into the gas chromatograph can cause flooding, which renders the gas chromatograph inoperative. The cost of repairing a flooded gas chromatograph is extremely expensive. Thus, the need for a low-cost device which reduces the incident of chromatograph flooding has increased.
A low-cost device which utilizes a ball-check valve assembly to prevent fluid flow into an air filter is disclosed in U.S. Pat. No. 5,213,586, entitled "Vent Check Valve," issued to Welker on May 25, 1993. The device is used with an odorant injection system and allows the free flow of air or gas therethrough during normal use and prevents the flow of fluid therefrom in the event of a system failure. The device includes an inlet opening, an outlet opening, and a flotation chamber with a floatable valve element positioned therebetween. When the system fails, the liquid level rises within the flotation chamber and the floatable valve element rises to a closed position in the top of the flotation chamber. The liquid is then prevented from overflowing into the air filter. A shortcoming of this device, however, is the fact that the user is unable to view the position of the floatable valve element within the flotation chamber. Furthermore, the configuration of the device does not allow for utilization with a chromatograph protector.
The use of flotation devices in glass tubes as viewable liquid level gauges is well-known in the art. For example, U.S. Pat. No. 1,373,129, entitled "Radiator Water Gauge," issued to Green et al., discloses an adjustable water gauge used to measure the amount of water in an automobile radiator. Other examples include: U.S. Pat. No. 2,554,100, entitled "Fluid Level Gauge," issued to Facchini, which allows the user to visibly determine the exact level of a fluid in a container at all times; U.S. Pat. No. 2,732,715 issued to Hawkins, entitled "Liquid Level Gauge," which is a gauge having a transparent tube at the exterior of a tank in which the liquid level of the tube is the same as in the tank; U.S. Pat. No. 2,833,148, entitled "Site Tank Gauge," issued to Hoyt, a site tank gauge in which the amount of fuel in a tractor can be measured; and, U.S. Pat. No. 5,052,224, entitled "Shielded Site Gauge for Storage Tanks," issued to Ford et al., which is a vertically mountable site gauge for visually determining the level or the volume, or both, of liquid stored in a container. Although these patents teach the use of flotation devices in glass tubes as viewable liquid level gauges, they do not teach the use of flotation devices in a transparent element as a viewable check valve.
With the above considerations in mind, it is an object of the present invention to provide a device which prevents the intrusion of liquids into a gas chromatograph.
It is a further object of the present invention to provide a device in which the user is able to visually determine the fluid level within the device at all times.